thesis

3
Author:
Benjamin Jagersma
School of Architecture
Victoria University of Wellington
jagersbenj@myvuw.ac.nz
Primary Supervisor:
Professor Brenda Vale
School of Architecture
Victoria University of Wellington
brenda.vale@vuw.ac.nz

4
Figure 1: Image of completed house in Washington DC

5
Abstract
Held every two years in Washington DC and run by the US Department of
Energy the Solar Decathlon is a competition that challenges architecture
and engineering students from all over the world to come up with new and
innovative ways to design and construct low energy homes. For the first
time in the competition’s history a team from New Zealand was selected
to compete in the 2011 competition. This thesis documents the design
process of the First Light house from concept to construction focusing on
the relationship between energy and architecture in a New Zealand home
designed for the Solar Decathlon.
The challenge for the young architects and engineers competing in the
competition is to develop ways of reducing energy consumption and to
raise awareness of the energy saving benefits of highly efficient home
design to the public. Despite this being the underlying philosophy, this
thesis suggests that the competition is structured in a way that rewards
technology over passive design innovation in architecture. A typical Solar
Decathlon house is epitomized by a large solar array generating the power
needing to run an oversized mechanical system. The New Zealand entry
challenges this trend with the design of a home that is focused on ways to
improve passive strategies for reducing energy use first before relying on
technology. The question is whether a home designed with this philosophy
in mind can still meet the strict requirements set out in the ten contests
embedded in the Solar Decathlon?
Designing a home to meet these requirements was also, in many ways,
contradictory to the house’s philosophy. The conceptual driver of the First
Light house was the iconic ‘kiwi bach.’ Commonly defined as “something
you built yourself, on land you don’t own, out of materials you borrowed
or stole,” the bach gives a unique model of comfort and how people
might live in a space. Its values are associated with a relationship with the
outdoors, a focus on the social aspects of the home and a simple use of
technology. As the project developed it was also apparent ‘the bach’, if it
were used all year round, could become a symbol for the current state of
many New Zealand homes; cold, damp, unhealthy and wasteful of energy.
Finding ways to improve this while maintaining the essence of the bach
became one of the major motivations throughout the design process. The

6
challenge with this was that the goals associated with designing a ‘kiwi
bach’ for a New Zealand climate were, in many ways, conﬂicting with the
requirements of the Solar Decathlon competition.
Using comprehensive thermal modelling the First Light house was
designed as a net zero energy home that could meet the requirements of
two quite unique briefs for two distinctly different climates. Throughout
this thesis the often contradictory relationship between the First Light
house as a Solar Decathlon entry and the First Light house as an energy
efficient ‘kiwi bach’ is explained. Broken into three parts the thesis looks
at the passive design of the home and the optimization of the building
envelope through thermal modelling, the active side of the design and the
generation of solar energy and ﬁnally documents the actual performance
of the house both in Wellington and in Washington DC during the
competition.

Contents
Abstract 5
1 Introduction 21
2 The starting point: The Schematic design proposal 25
2.1 The State of housing in New Zealand 25
2.2 The team 26
2.3 The Concept 28
2.4 The site 29
2.5 The competition 32
2.5.1 Judged contests 32
• Architecture
• Engineering
• Affordability
2.5.2 Measured contests 33
• Comfort zone
• Hot water, Appliances and Home Entertainment
• Energy balance
2.6 The house – The initial design 36
2.6.1 Technologies and energy use 39
2.7 The objective 40
2.8 The method 40
3 Comfort zone and Climate 43
3.1 An introduction to thermal comfort 43
3.2 Climate 46
3.3 Thermal modeling - Assumptions 49
3.3.1 Construction 49
3.3.2 Heating and Internal Gains 50
3.3.3 Air exchange – Ventilation and inﬁltration 50
3.3.4 Modeling Variations 50
4 Insulation 53
5 Thermal mass 59

6 Glazing and skylight 65
6.1 Skylight Glazing 70
6.2 Skylight Shading 75
6.3 Window Glazing 78
7 Passive cooling: Shading and Ventilation 83
7.1 Shading 83
7.2 Ventilation 88
8 Mechanical system 91
8.1 The ﬁnal model 91
8.1.1 HVAC performance speciﬁcation 93
8.2 Mechanical system design 94
8.3 Comfort Zone energy use 96
9 Energy use 101
9.1 Hot water 103
9.2 Appliances 108
9.3 Home entertainment 111
9.4Total energy use 113
10 Energy generation 117
10.1Conclusion 124
11 Results 127
11.1 Frank Kitts Park 127
12 Competition results 133
12.1 Day 1: 22nd September 137
12.2 Day 2: 23rd September 141
12.3 Day 3: 24th September 145
12.8 Day 8: 29th Spetember 163
12.10 Day 10: 1st October 171
12.11 Summary 173
13 Conclusion 177
14 Bibliography 184
15 Appendix A - Contest rules 187

9
22 Appendix B: Calculation of R value 198
22.1 Roof construction 199
22.2 Wall construction 200
22.3 Concrete floor construction 201
22.4 Timber floor construction 202
22.5 Window and Skylight 203
16 Appendix C: Weather file 204
23 Appendix D: Schedule of contests 205
17 Appendix E: Drying cupboard tests 215
17.1 Test 1: Water temperature 80o
C 215
18 Appendix F: Dinner party energy use 219
18.1 Dinner Party 1 219
18.2 Dinner party 2 220
19 Appendix G: total house energy use 221
20 Appendix H: Energy generation report 222
21 Appendix J: Judged contest results and comments 226
22 Appendix K: Schematic design proposal 230

10
List of ﬁgures
Many of the images used throughout this thesis are photographs taken
by the First Light team as a part of the project. All images below where a
source has not been given have been credited to First Light
Figure 1: Image of completed house in Washington DC 4
Figure 2: The team celebrating second place in Architecture outside the
Capitol building in Washington DC 19
Figure 3: The First Light brand 20
Figure 4: Artistic impression of conceptual design 22
Figure 5: Conceptual design models of 2011 Solar Decathlon teams 23
Figure 6: The solar canopy 24
Figure 7: Energy use of a typical New Zealand home. Source: (Isaacs,
Camilleri, et al. 2010) 26
Figure 8: A Traditional kiwi bach 28
Figure 9: Site plan (Source: US Department of Energy) 30
Figure 10: Site location plan (Source: US Department of energy) 31
Figure 14: Diagram of how people loose heat from their bodies (Source:
Lechner 2009) 44
Figure 15: Comparison of temperature and humidity in Wellington and
Washington DC (Source: Autodesk, Ecotect analysis 2011) 47
Figure 16: Graph of temperatures in New Zealand throughout the entire
year compared with Washington DC 48
Figure 17: Figure in here 48
Figure 18: Ecowool insulation arrives at the construction site in Lyal Bay
52
Figure 19: Comparison of variation in annual maximum, mean and
minimum internal temperatures (°C) due to increase in insulation R-value
(m2
°C/W) 54
Figure 20: HVAC energy use during competition with an increase in
insulation R value (m2
°C/W) 55
Figure 21: Installation of wool insulation 56
Figure 22: Installed wool insulation in roof and wall 57
Figure 25: Variation in minimum, mean and maximum annual internal

11
temperature with the addition of a concrete topping to the floor 60
Figure 26: Variations in HVAC energy use with 100mm concrete slab
compared with baseline for the period from September 15 – October 15
61
Figure 27: Variations in hourly internal temperature with 100mm and
800mm (9.3” & 31.5”) concrete slab compared with baseline for the
period from September 15 – October 15 62
Figure 28: Craning the modules into place on Frank Kitts Park 62
Figure 29: Detailing of the concrete floor and timber decking 63
Figure 30: The skylight 64
Figure 31: Annual maximum, mean and minimum internal temperature
(°C) with glazing area between 0% and 100% of baseline area 66
Figure 32: Variations in hourly internal temperature with glazing area
between 0% and 100% of baseline area concrete slab compared with
exterior for the period from September 15 – October 15. 67
Figure 33: Variations in hourly internal temperature with glazing area
between 100% and 400% of baseline area concrete slab compared with
exterior for the period from September 15 – October 15. 68
Figure 34: Artist’s impression of the architectural impact of central
space showing the skylight 69
Figure 35: Composite skylight glazing construction details (a) Triple
Layer Danpalon with translucent glass wool insulation, (b) Profilit glass
channel with nano-gel insulation, (c) ETFE 4 layer pillow 71
Figure 38: Daylight anaylsis of the skylight preformed in Autodesk
Ecotect Analysis software 74
Figure 39: Comparison of annual maximum, mean and minimum
internal temperatures (°C) with various shading devices 76
Figure 40: Energy consumption in New Zealand with interior, exterior
and twin shading options 77
Figure 41: Energy consumption during competition with interior,
exterior and twin shading options 77
Figure 43: Maximum heat gain and loss through the window glazing
over entire year 80
Figure 45: Thermal image of bifold doors, North facing glazing and
skylight of the First Light house (Source: Image courtesy of BRANZ) 81
Figure 47: At 1200mm the Canopy provides full shading on December
21st in New Zealand and on June 21st the canopy is sized to allow full
solar gain throughout the day 84
Figure 52: Angle of installed canopy slats 87

12
Figure 56: Incremental construction of the ﬁnal ‘super model’ 92
Figure 57: Simulated heating and cooling loads (kW) of HVAC system
from August to October in Washington DC 93
Figure 60: Daily energy consumption (kWh) of HVAC system during
competition under the simulated weather scenario; hot, calm and raining
99
Figure 61: Monthly energy use of the HVAC system (kWh) in Wellington,
New Zealand 99
Figure 62: Part of the house’s energy monitering system (TRING) that
represents energy use by the size of ‘tree rings’ 100
Figure 63: Evacuated tube solar hot water collectors 102
Figure 64: Parabolic solar collector (Source: Image courtesy of Anrew
Wallace) 104
Figure 65: Hourly output (W) of Evacuated tube and Flat plate solar
hot water systems on an average and 10% low day of solar radiation in
New Zealand 104
Figure 66: Diagram of hydronic drying cupboard 105
Figure 67: Images of dryer mock up used for the intial tests 106
Figure 68: Diagram of Hot Water system 107
Figure 69: Completed drying cupboard 109
Figure 70: Fisher and Paykel applainces 110
Figure 71: Guests enjoying the ﬁrst dinner party in the First Light house
112
Figure 72: Energy use per day during the competition period 113
Figure 73: Pie graph of energy use during competition 114
Figure 74: Graph of the monthly energy consumption (kWh) of the
First Light house throughout year in New Zealand 115
Figure 75: 225W Polycrystalline solar panels 116
Figure 76: Schematic diagram of First Light electrical system 117
Figure 77: Probability density function 118
Figure 78: Diagram of intial panel layout and spacing on canopy 120
Figure 79: Energy generation of solar array at different angles
throughout the year in Wellington 121
Figure 80: Simulated energy consumption vs generation using weather
data from September 2005 121
Figure 81: Energy consumption vs generation throughout year in New
Zealand 123
Figure 82: First Light house on Frank Kitts park from above 125
Figure 83: Interior completed ready for public tours 126

13
Figure 84: Panoramic image of First Light house on Frank Kitts Park 127
Figure 85: Student construction on Frank Kitts park 128
Figure 86: Students giving public tours through the house 128
Figure 87: Lines of people waiting to view the house 129
Figure 88: Faulty seal at the base of the bifold doors (Source: Image
courtesy of BRANZ) 130
Figure 89: Blower door test on the First Light house 131
Figure 90: Final team photo before the house was shipped to DC for
the competition 131
Figure 91: Completed house in Washington DC 132
Figure 92: Temperature and Humidity sensor 134
Figure 93: Observer preforming spot check of sensors 134
Figure 94: Decathlete reading flow meter while preforming a hot water
draw off 135
Figure 95: Observer monitering hot water draw off 135
Figure 96: September 22 peformance anaylsis 136
Figure 97: Team scores at the end of Day 1 of the competition 137
Figure 98: Signage ready the first public tours 138
Figure 99: Energy use of all 20 teams throughout on the 22 September,
the first day of the competition 139
Figure 102: Temperature of New Zealand house compared with the
three leading teams in the comfort zone contest 142
Figure 103: Relative humidity of the top 7 teams during the scoring
period of the 23 September 142
Figure 104: Energy balance of New Zealand compared with the top
three teams by the end of the 23rd
of September 143
Figure 107: Graph of top three teams humidity during score period
compared with New Zealand 146
Figure 108: Public lining up to view the house despiet the rain 147
Figure 111: The team ready for another day of tours and grey skies 150
Figure 112: Energy balance of all teams on day 4 151
Figure 113: New Zealand’s energy balance compared with top three
teams on September 24th 151

14
Figure 118: The team awaiting announcement of the affordability
contest results 156
Figure 121: Architecture competition results 160
Figure 122: Energy balance on 28th September of top six teams 161
Figure 125: Architecture competition results 164
Figure 126: Energy balance on 28th September of top six teams 165
Figure 128: Celebration after winning engineering contest 167
Figure 130: Graph of the accumulation of points throughout
competition 168
Figure 131: Final energy balance of top 6 teams 169
Figure 132: Final placings in the 2011 Solae Decathlon 170
Figure 134: Team Celebrations after ﬁnishing in third place 172
Figure 135: Summary of Final results 173
Figure 136: New Zealand’s cumulative energy use throughout the
competition period 174
Figure 137: Actual points earned versus potential points for each
individual contest 175
Figure 138: NZ Flag outside the First Light house 176
Figure 139: Measured contest scores versus judged contests 178
Figure 140: Brendan, Eli and Nick with Joe outside the teams HQ during
the competition 180
Figure 141: Final interior image 185

16
List of tables
Table 1: Construction R-Values used for baseline simulation 49
Table 2: NZ Building code requirement of R-value for ceiling, wall, floor
& glazing (Source: Isaacs, Thermal Insulation 2007, 110 53
Table 3: Thickness of polystyrene and the corresponding R-Value
(m2
°C/W) 54
Table 4: Construction R-value of individual building elements 57
Table 5: Total heating and cooling energy of the house with skylight
compared with no skylight during the competition period 68
Table 6: Thermal and optical specifications for various glazing types
(source: Window 5) 70
Table 7: Thermal and optical properties of composite skylight glazing
options 71
Table 8: Thermal and optical specifications for Metro Glasstech intial
suggested IGU (source: Metro Glasstech and Window 5) 74
Table 9: Thermal and optical specifications for various glazing types
(source: Window 5) 79
Table 10: Construction R-value of glazing and skylight 91
Table 11: Percentage shading of south facing windows of canopy
louvers at various angles 91
Table 12: Construction R-Values used for final simulation 91
Table 13: Conditions of worst case weather file 98
Table 14: Estimated energy use of comfort zone contest 98
Table 15: Estimated energy use for hot water contest 103
Table 16: Estimated energy use for hot water contest 108
Table 17: Estimated energy use for Home entertainment contest 111
Table 18: Total Estimated energy use of the First Light house during the
competition 113
Table 19: Estimated energy generation versus consumption during the
2005 competition 121
Table 20: Total monthly energy generation versus consumption in
Wellington 122
Table 21: Thermal resistance of individual building elements 198
Table 22: Breakdown of the layers within the roof construction and their
R values 199

17
Table 23: Breakdown of the layers within the wall construction and their R values 201
Table 24: Breakdown of the layers within the floor construction and their R values 202
Table 25: Breakdown of the layers within the timber floor construction and their R values 203
Table 26: Construction of weather files 204
Table 27: Test results of prototype dryer 216
Table 28: Energy use of first dinner party 219
Table 29: Energy use of second dinner party 220
Table 30: Total competition energy use per day 221

18
Acknowledgements
This project would not have been possible if it wasn’t for the tremendous
help and support from many wonderful people from around New Zealand.
For me, this journey began late in 2009 and throughout I have been
honoured to have met and worked with some amazing individuals both in
the industry and within the university
Firstly, to all of our sponsors thank you for your support and guidance
throughout the project. To successfully design, build and transport a small
solar powered home to Washington DC, not to mention ﬁnishing in the top
three teams, is a huge accomplishment and would not have been possible
without you. One of the elements that have made this project successful
is the collaboration between the university and industry in New Zealand.
Many people have been involved throughout the design and construction,
often giving their time, expertise and materials in kind to help the project.
For me, personally I have made some great friends and contacts that I
look forward to working with in the future.
Thank you to Victoria University of Wellington for your continued support
throughout the entire project both individually and to the whole team.
Individually the ﬁnancial support provided by the university was extremely
helpful and meant our full focus could be put into the research, design,
and construction of a successful entry into the competition. This project
is unique and was a huge learning process for all. Many people from
within the university have been involved in the project in a wide range
of capacities and I am grateful for all of your help, guidance and support
along the way.
I would also like to acknowledge my supervisor Brenda Vale. Your positive
encouragement and detailed focus, especially during the last six weeks of
the written phase of the thesis has been greatly appreciated. Brenda and
Robert, thank you also for all of the help you have given us throughout
the last two years. We have all learnt so much from your tremendous
knowledge.
Thank you to Anna, Eli and Nick. It is difficult to describe the enormous
respect and appreciation I have for you all as architects. Over the last
two years we have been through it all, and come out the other end great

19
Figure 2: The team celebrating second place in Architecture outside the Capitol
building in Washington DC
friends. I look am excited about working with you in the future and can’t
wait for First Light 2012!
Throughout the project a team of students also worked on the project. To
the entire team thank you for your hard work and tireless commitment.
You made this project a success! Speciﬁc regard goes to Liam, Andrew,
Rob and Josh who I worked closely with throughout the simulation phase
of the project and whose results have made a large contribution to this
research. Thank you for your help and your guidance. For an architect,
venturing into the world of simulation and building science was initially
daunting but greatly rewarding, and having your support throughout is
greatly appreciated.
Finally, thank you to my family and friends for your personal support, in
particular my partner Amanda for your smiles and laughter. You got me
through!

Figure 3: The First Light brand

21
1 Introduction
In September 2011, twenty university led teams from all over the world
descended on West Potomic Park in Washington DC to compete in the
US Department of Energy’s (DOE) Solar Decathlon. The competition
challenges teams to design, build and operate a small, net zero energy
home that is built off site, transported to Washington DC and constructed
there in less than seven days. Once complete, the houses form a solar
village where they are monitored, measured and judged in ten unique
contests over the course of ten days. During this period the houses are
open to the public when thousands of people make the journey to the
banks of the Potomac River to experience these unique and innovative
solar powered homes.
First held in 2002, there have since been 91 decathlon homes constructed
and set up in Washington DC as a part of the competition. Since its
inception it has grown to become one of the most anticipated design
competitions ever held. For the 2011 Solar Decathlon teams were selected
from a rigorous two stage application process that involved the submission
of an initial proposal by the university followed by a conceptual design
presentation and 1:50 scale model of the proposed design (Figure 5). This
process took over three months but by early 2010 the teams that had
been selected for the 2011 competition had been announced. One of the
finalists was a small ‘kiwi bach’ from Victoria University in Wellington, New
Zealand. Being the first ever country from the southern hemisphere in the
competition and the first country in the world to see the light every day
it was appropriate that the team was named First Light. Once they were
selected the team had less than two years to develop the house from
the conceptual design into a fully functioning, net zero energy home that
could be constructed in Washington DC.
This thesis focuses on the energy use of the house and documents the
design process from the initial selection into the competition through to
final construction and the overall performance of the house during its
time in Washington DC. Through comprehensive thermal modelling the
thesis looks at how both the passive and active design of the house has

22
been optimized to reduce its energy use in New Zealand as well as meet
the requirements of the ﬁve measured contests in the Solar Decathlon.
Designed with the same rigour as a yacht the First Light house was
constructed in September 2011, in Washington DC, where it was sailed for
ten days under a strict set of rules, in a speciﬁc climate against nineteen
other teams but, instead of using the wind, it was powered by the sun.
Figure 4: Artistic impression of conceptual design

23
Figure 5: Conceptual design models of 2011 Solar Decathlon teams

25
2 The starting point: The
Schematic design proposal
2.1 The State of housing in New Zealand
The starting point for the ideas associated with the First Light house arose
out of the current state of housing in New Zealand. Although much of the
focus over the last two years was on designing a home that best met the
requirements of the competition a major focus was on the performance
of the house back home in New Zealand. It was essential that the house
that was presented in the 2011 Solar Decathlon was based on kiwi ideals
designed for a New Zealand climate. At present New Zealand homes
are cold, damp, and unhealthy and consume large amounts of energy.
A recent study performed by the Building Research Authority in New
Zealand, the Household Energy End-use study, (HEEP) quantiﬁed how,
where and why energy was being used in New Zealand homes, based on
monitoring of energy and end uses in a national sample of 400 homes.
The study found that the average total energy use per household was
11,410 kWh/yr (Isaacs, Camilleri, et al. 2010, 13). Of this energy used in
homes over a third was being used to keep them warm, on average using
3,820kWh/yr (Isaacs, Camilleri, et al. 2010, 15).
The study went into detail about how this energy was being use. It found
that despite using this average energy for space heating New Zealand
homes were extremely cold. Based on the data from the study it was
found the mean indoor ambient winter temperature of the houses studied
was well below the World Health Organisation (WHO) healthy indoor
temperature range of between 18-24o
C (WHO 1987, 14). These low indoor
temperatures are associated with poor health, a variety of social and
economic problems and contribute to mould and dampness in houses.
The study concluded that there are three critical factors that contribute to
low indoor temperatures; thermal performance of the building envelope,
the type and source of heating, and how heating is used. By looking
into how, why and when people use energy the study has been able to
CHAPTER

26
highlight that reducing heat lost through the building envelope and the
implementation of more efficient means of heating could reduce the
energy wasted in unsuccessfully ‘heating’ New Zealand homes.
In order to design a net zero energy home that would meet the competition
requirements it was essential to reduce the energy consumption of every
aspect of the building design. As space heating is the biggest energy
consumer in an average NZ home, focusing on ways to reduce this through
passive design strategies would not only improve the New Zealand
situation but would also help to meet the comfort requirements of the
Solar Decathlon. The aim was to use the constraints of the competition
to design a healthy, comfortable and zero energy home that was ideal for
New Zealand conditions.
2.2 The team
After being selected to compete the First Light house began its
transformation from an initial concept dreamed up by four architectural
students into a real, energy self-sufficient home. The ﬁrst step was to
put together a schematic design proposal that was submitted to the US
Department of Energy that described the design in its current form, the
objectives of the project and a methodology for developing the design.
This document was compiled by the four graduate students who had
HHot water
29%
Light
8%
ting
%
Oth
C
her appliances
13%
Refrigerat
10%
Cooking
6%
s
ion
8%%%%
Othhe
C
%
13%
Refrigeration
10%
ookingCCo
6%
HHot waater
Space hea
34%
ting
TheaverageNZhomeuses3820kWh/yrforspaceheatingalone
Figure 7: Energy use of a typical New Zealand home. Source: (Isaacs, Camilleri,
et al. 2010)

27
developed the concept design as a part of a studio paper in the final year
of their architecture degree.
Before developing the proposal and the subsequent design the project
was split into four clearly defined areas of research. These comprised
architecture and logistics, interior design and landscape, marketing and
communications, and finally engineering and technologies. By separating
the project into four areas of research the team could focus more rigorously
on the development of the design to meet the performance criteria of
the contests embedded in each area of research. This would push the
boundaries of the initial design concept and create a more evolved design
that would perform optimally in all 10 contests within the competition.

28
2.3 The Concept
Before investigating the concept design of the First Light house it is
worth introducing the ideas that have been essential to its design over
the past two years. Below is a quote from the schematic design proposal
(Appendix K) that was submitted to the organizers in March 2010, at the
beginning of the project. This proposal was the ﬁrst document to explain
the concept design in its entirety.
“…The iconic “Kiwi bach” provided a perfect precedent for identifying
the core values behind a uniquely New Zealand lifestyle. Traditionally
situated in remote locations, the bach was a refuge away from city life.
Here, recreation and socialization were a priority. As primarily a summer
destination, life at the bach took place as much outside, on large decks
and patios, as it did inside. This resulted in a seemingly modest house with
open plan living, simple amenities, and shared accommodation. Our house
brings these ideals of bach life into a contemporary setting, providing a
permanent residence where recreation and social activities are united with
a simple use of technologies.”
From this initial design statement there are three core values that were
extracted to form the foundation of the design;
• Relationship with the outdoors
• Focus on socialisation
• Use of simple technologies.
Figure 8: A Traditional kiwi bach

29
Throughout the process these core values have been used as a way of
focusing the design. By separating the project into four separate areas
there was the potential to drift away from the original concept. Whenever
the research pushed the design in a particular direction, these values were
used as guidelines to evaluate design decisions. But within these original
values there is very little about a concept for energy use within the house.
It is discussed throughout the document but is never stated as being an
explicit driver of the design. It is understood in the proposal that in order
to compete in the competition the house must be net zero energy (ie.
it must generate at least as energy much as it uses). The proposal did
discuss the fact that reducing the energy the house consumes would have
a direct influence on its cost.
“If we can achieve our desired energy consumption, we will be able to
reduce the number of solar panels on the roof. This will have a dramatic
impact on the affordability of the home and will make it more accessible
to a wider range of individuals in both New Zealand and the US.”
The development of the design from this initial proposal very quickly
became about balancing design decisions with their direct effect on the
overall energy use of the house and therefore its cost. Although it is not
explicitly stated within the schematic design proposal, energy use was as
much of an influence on the design as the three original core values.
2.4 The site
There are two quite distinctly different sites for the First Light house. The
first is a flat site, 23.8x18.3m (78’x 60’) square, located in West Potomac
Park, in Washington DC. Originally the competition site was to be the
National Mall between the Capitol building and the Washington Monument
but this was changed mid-way through the project to West Potomac Park.
(Figure 10) The site, on the banks of the Potomac River, is situated along
the path between the Lincoln and Jefferson Memorials. It gets full access
to all day sun and has beautiful views across the river. The layout of the
competition village was split into five streets running east-west with four
houses on each. Each site faced due south (Figure 9) and was governed
by a solar envelope that restricted the size and the height of the house
within the site boundary.

30
The other site was a hypothetical section of the same dimensions in
Wellington, New Zealand. For the purposes of this project a speciﬁc site
within Wellington was not chosen but it was assumed it would have the
same site parameters as for the competition.
The location of the site was extremely important for the start of the
investigation into the performance of the house within a particular climate.
For the purposes of this project the design of the house was optimized for
both climates at different times of the year. This will be explained in more
detail later on.
Figure 9: Site plan (Source: US Department of Energy)

31
Figure 10: Site location plan (Source: US Department of energy)
395
66
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George W
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Independence Ave.
14St.NW
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White House
Jefferson
Memorial
Lincoln
Memorial
Martin Luther
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Memorial
Franklin Delano
Roosevelt Memorial
W
est
Basin
Dr. SW
Potomac River
Tidal Basin
U.S. Department of Energy Solar Decathlon 2011
National Mall West Potomac Park
See Inset
Washington
Monument
Franklin Delano
Roosevelt Memorial
Potomac River
Tidal Basin
Ohio
Dr. SW
Rock Creek Park Trails
W
estB
asin Dr. SW
W
estB
asin Dr. SW
U.S. Department of Energy
Solar Decathlon 2011
National Mall West Potomac Park
2011

32
2.5 The competition
Often considered the Olympics of house design and being a Decathlon
the competition is split into 10, equally rated contests, made up of
architecture, engineering, affordability, communications, market appeal,
comfort zone, hot water, appliances, home entertainment and energy
balance. Worth 100 points each, the contests are split into five judged and
five measured contests each with a very specific set of requirements. The
creator and director of the Solar Decathlon, Richard King stated “the aim
of the competition is to raise awareness’s of the energy saving benefits of
highly efficient home design and renewable energy technologies.” When
developing the concept for the competition King came up with a concept
of 10 different contests that together challenged teams to design a home
that would best achieve this aim. Appendix A gives further details about
the specific requirements of each contest.
2.5.1 Judged contests
The judged competitions were adjudicated by a panel of ‘experts’ in each
particular field who critique the homes based on the drawings, images
and marketing material and on the quality of the houses in the first two
days of the competition. The results are announced incrementally over the
course of the competition.
• Architecture
The architecture contest was judged by a team of ‘esteemed architects’
who focused on five specific areas of the design. These included the
architectural elements such as scale and proportion of the space, its
holistic design, lighting, inspiration, and finally the documentation of
the drawings and the specification. Worth only 100 points, it was rated
with the same importance as home entertainment and hot water. In 2007
architecture was worth 200 points but was reduced back to 100 for the
2009 and 2011 competitions. Unfortunately, there is no mention in the
marking schedule or reward for the use of passive design strategies.

33
• Engineering
Like architecture, the judging of the engineering contest is based on
five categories. In the Solar Decathlon the engineering is specifically
focused on the HVAC system. A team of judges look ‘under the hood’
of the home and establish the functionality, efficiency and reliability of
the mechanical systems. Unique, innovative solutions are encouraged and
clear documentation was imperative. But, being specifically focused on
the mechanical systems there is no mention of the engineering involved
with transporting the house and, like the architecture competition, there
is no specific mention of the passive design elements. Although the
functionality and efficiency of the HVAC system would improve with a
well-designed thermal envelope there was no direct mention of passive
systems within the rules but instead a very distinct focus on technologies.
• Affordability
New to the 2011 competition the affordability contest was introduced to
encourage teams to design and build affordable homes that combine
energy efficient construction and appliances with renewable energy
technologies. In the past, with no limits to affordability, the teams that
were competitive in the Decathlon were those that had large budgets
and could afford the latest in cutting edge technology. The aim of the
affordability contest was to put the focus back on the design of the home
rather than the technologies within it. By doing this the US Department
of Energy hoped to encourage consumers to adapt and introduce the
energy saving techniques displayed by the teams into their own homes
and building projects. Unfortunately the cost limits set by the competition
were still relatively high, especially considering the size of the houses.
2.5.2 Measured contests
The measured competitions monitor how each house performs against
a very specific set of criteria in Washington DC during the 10 days of
the competition. This thesis focuses on the measure contests in the Solar
Decathlon and documents how the First Light house has been designed
to meet each of the requirements of all five of the measured contests as
outlined below.

34
• Comfort zone
The comfort zone is one of the toughest of all 10 contests within the Solar
Decathlon and a major part of this thesis is concerned with this one issue.
The Solar Decathlon challenges teams to design a home that remains
within an extremely limited temperature and humidity range throughout
the competition. Sensors placed throughout the home monitor the
temperature and humidity every fifteen minutes over the contest week.
To be eligible for full points teams must maintain a comfort zone between
21.7o
C and 24.4o
C and below 60% relative humidity over the monitored
period. These narrow comfort parameters are significantly lower than
what is typical in the majority of energy efficient buildings around the
world. The question is what effect do these narrow comfort requirements
have on the design of a Solar Decathlon house and its subsequent energy
use?
• Hot water, Appliances and Home Entertainment
The sporting metaphor often used to describe the contests within the
Solar Decathlon is extremely relevant in the Hot water, Appliances and
Home Entertainment contests. These contests turn activities like the
production of hot water, washing and drying clothes and the running of
the refrigerator into standalone events worth points in the competition.
Like the comfort zone contests each has a very specific set of rules that
teams must meet to be eligible for full points. In reality these contests
in combination with the comfort zone form a method for simulating the
typical energy use of a house as a way to distinguish the subsequent
energy efficiency of each of the houses in the Solar Decathlon. But the
heavy weighting of points in these three contests, 30% of the overall
score, make them more important than the architecture and engineering
contests combined.
• Energy balance
The final measured competition is the energy balance contest. Throughout
the competition a bi-directional energy meter monitors the energy
production and consumption of each house. To receive full points each
house must generate at least as much energy as it consumes over the
course of the 10 days of the competition, whatever the weather.

35
With the innovative homes that are produced and the public awareness
the competition attracts the Solar Decathlon has grown to become one of
the most anticipated design competitions ever held.

36
2.6 The house – The initial design
Once the space the house could occupy within the site boundary, the rules
were understood and the competition requirements were ascertained the
plan of the house could be developed. Due the size restraints for the floor
plan governed by the competition rules, and the need to pack the house
into containers for shipping, there had to be an economy in planning that
made use of all the space available. The plan is based on a simple, compact
form with two closed-in pavilions that house the sleeping and study space
surrounding a central eating area. (Figure 11)
“A long box, cut in half creates the living end and the sleeping end. In the
cut, the bi-section, lie the dining room and the kitchen (the eating bit)”
The three major functions of the home—living, eating and sleeping—fitted
within a single space that ran along the ‘sunny-side’ of the house. The living
end of the home was designed around a built-in couch that transformed
into a sleeping space for extra guests. The sleeping end was separated by
a study unit which divided the room, adding privacy to the bedroom. The
eating space in the centre was the entry, central meeting area, kitchen and
dining space. It was the ‘social’ heart of the home as well as the vehicle
for connecting with the outdoors. In the original design this central space
was fully glazed, with a transparent roof, no shading and large bi-folding
doors on either side. (Figure 12) This space captured the essence of the
three core values of the project and was a major conceptual driver of
the design. Along the ‘cold’ side of the house ran the services core that
housed the bathroom, laundry, and kitchen. Moving the more discrete
functions to this side of the house was a deliberate passive design feature
which added another layer of insulation against the cold on the outside
and allowed the living, dining and eating spaces to make the most of the
sun throughout the day.
The schematic design proposal briefly discussed the passive design
features of the house, and concluded that they were a major driver of
the design. Although not specifically stated the general idea presented
within the proposal was that reducing space heating and cooling energy
use through passive solar design features would reduce the overall energy
demand of the house. The original concept was designed with triple

37
Figure 11: Conceptual ﬂoor plan of the First Light house
“Alongbox,cut inhalf creates thelivingendand thesleepingend.
In thecut, thebi-section,lie thediningroomand thekitchen(the
eatingbit)”

38
glazed windows and high levels of insulation within the building envelope
to reduce heat loss. A ‘solar’ canopy, designed to provide shading of the
large windows during the summer months and maximise solar gain during
the winter, became the main passive solar design feature. This timber
canopy gave the house its unique form as well as providing the structure
for the solar panels, lifting them up off the building envelope. At this stage
of the design process there had been very little use of computer models
for thermal simulation. The proposal concluded that the next step in the
design would be to create a model that could be used to optimize the
building envelope and improve the performance of the passive design of
the house.
Figure 12: Intial interior renders of First Light house

39
2.6.1 Technologies and energy use
Despite not having completed any thermal simulations there had been
some basic calculations on energy use which had been used to size the
solar array. It was estimated that 33 monocrystalline solar panels were
needed to generate all of the energy the house would consume during
the competition. As a back up to this the design proposed the use of
dye-sensitized solar cells detailed into a sliding façade. Through a simple
calculation of the daily energy consumption based on the competition
schedule it was estimated at this early stage that the house would consume
12-14kWh per day. Interestingly from this early phase of the design there
was a discussion about the need to improve the performance of the
heating and cooling system in order to reduce this energy consumption.
“Considering the huge role heating and cooling have on the energy
consumption of the house, designing a simple system that uses small
amounts of power to achieve the thermal comfort outlined in the
competition will go a long way to reducing our total energy consumption”
The heating and cooling system described in the initial design was a
simple solution of two wall mounted heat pumps on either side of the
central space. There was a strong emphasis on automation and control
in this initial concept through a centralised building management system.
This would control the house and provide information to the user about
energy and water consumption. Along with LED lighting and energy
efficient appliances, an evacuated tube solar hot water system was used
to generate all of the hot water for the home. Although there is little
science behind any of the decisions made up until this point the ideas
relating to both the building and the technologies within it formed a solid
foundation for reﬁnement. The next step discussed in the proposal was to
use this information to form a comprehensive model that could be used
for thermal and energy simulation to determine accurately how the house
would perform and how it could be improved.

40
2.7 The objective
With this starting point in the schematic design proposal it was essential
that the goals of the project were outlined. With the split into four distinct
areas of research there were four different ways of working towards the
two goals of winning the 2011 Solar Decathlon and improving house
design in New Zealand. In order to achieve these, the design would
have to meet the requirements of all ten competitions within the Solar
Decathlon. This thesis looks at the engineering of the overall design of
the First Light house, an element that is integral to success in the Solar
Decathlon. From the engineering side of the project the goals were
simple—design a house that both during the competition and over an
entire year in NZ would use less energy than it generates. To do this, four
other measured competitions, comfort zone, hot water, appliances and
home entertainment became critical to the overall design because they
were linked to energy use. Using the schematic design as the starting
point and focusing on the requirements of each of the measured contests
the design was developed to meet these goals.
2.8 The method
The method for developing the concept design into a net zero energy
home began with a systematic approach to improving the efficiency of
every element of the design. All four of the relevant measured contests
were analysed in depth starting with the thermal comfort competition.
This thesis is in part the story of this development. Chapter 3 looks at
how the schematic design was translated into a computer model that
was run through thermal simulation software in order to ﬁnd areas where
the building envelope could be improved. Once this baseline model was
constructed simulations concentrated on reducing heating and cooling
loads while maintaining thermal comfort using passive design strategies.
The thermal comfort goal used during the ﬁrst phase of simulations was
the temperature and humidity requirements set for the contest (21.7o
C-
24.4o
C and below 60%RH). Using the baseline model, several variations
were made to the building fabric in order to reduce heating and cooling
loads. These variations were:

41
• Envelope insulation levels – Chapter 4
• High or low mass flooring – Chapter 5
• Glazing and skylight – Chapter 6
• Shading and ventilation – Chapter 7
The model was run through two different energy simulation programs and
results were analyzed separately to ensure the accuracy of the observed
trends. Once an optimal envelope was established a ‘super model’ (final
computer model) was created that represented the final design that
would be constructed. With the super model created Chapter 8 discusses
how this was used to simulate the performance of the heating and cooling
system in the house during a number of different climatic conditions for
both the competition in Washington DC and in Wellington. This information
was used to size the mechanical system for the house appropriately and
to calculate its energy use.
After establishing the best method for reducing energy use in the thermal
comfort competition the same process was completed for hot water,
appliances, and home entertainment as discussed in Chapter 9. Each
element of all three contests was analysed to find areas where energy
could be saved. Once performance was optimized the information was
put into a final simulation that included everything in the house that would
consume power. This gave an accurate estimate of energy use, from which
the size of the solar array could be calculated, as shown in Chapter 10.
The process described above was focused entirely on reducing the overall
energy use of the house. As this is only one aspect of the overall design,
compromises in performance were made to ensure the overall goals of
the project were met. In the chapters this process will be explained in
more detail. Information on the simulated performance of the house
and how this affected the design process will be explained. The thesis
concludes with Chapter 11 and 12 which analyses the actual performance
of the house both during the competition and when it was set up in New
Zealand in Frank Kitts Park.

42 Figure 13: Thermal image of First Light house bedroom
(Source: Image courtesy of BRANZ)

43
PASSIVE DESIGN
3 Comfort zone and Climate
3.1 An introduction to thermal comfort
“Thermal comfort – that condition of mind which expresses satisfaction
with the thermal environment” (ASHRAE Standard 2003, 7)
The traditional kiwi bach or holiday home, from which the concept for
the First Light house developed, was a place not designed for thermal
comfort all year round since it was normally occupied in the summer. For
a competition with strict comfort criteria it is perhaps ironic that the ‘kiwi
bach’ was used as the conceptual driver. In fact the non-conventional
nature of the bach is enshrined in the common definition as “something
you built yourself, on land you don’t own, out of materials you borrowed
or stole.” (In turn, this definition seemed quite fitting for the project; a
student built house, on a Washington DC park, from materials that were
borrowed or donated.) In the bach there was no need for strict comfort
controls. On sunny days when it was too hot to be inside, all the doors and
windows would be open and the occupants would be dressed in shorts
and t-shirts, sitting outside on the deck. If it was too cold the users would
be dressed in long pants and Swanndris (a New Zealand woollen shirt),
snuggled up under a blanket with a hot water bottle on the couch. In
terms of the Solar Decathlon definition of comfort, therefore, the bach is
not a great model on which to base the design of an energy efficient solar
powered house. The nostalgic memory of getting home from the beach
and having to open up all the doors and windows and wait 15mins before
going inside the house because it was unbearably hot, is not associated
with good building design. However, although the bach envelope did
not provide a model for reducing energy use, how people lived in the
space did. Within the bach occupants had full control over their space.
If it was too hot people opened the doors and windows. If it was too
cold they closed the blinds and put on another jersey. People acclimatized
CHAPTER

44
to a wider comfort band without the reliance on energy for heating and
cooling. This posed an interesting challenge for the design of the First
Light house. Could there be a way to translate the values associated with
comfort in the traditional ‘kiwi bach’ to a house designed to meet a strict
set of comfort requirements for a competition in Washington DC?
The thermal comfort zone is the range of temperatures and humidity within
which people feel comfortable. It is easy to measure the temperature and
humidity in a room but it is more difficult to say at what temperature
a person feels comfortable. Imagine a family in autumn who made the
journey to the bach for the Easter weekend eager to make the most of the
last weekend before winter. Late one evening, sitting around the kitchen
table playing New Zealand monopoly they do not notice the drop in room
temperature that has occurred since the sun has set. The game is nearing
its end and it is has become competitive; the parents both have a glass
of NZ wine and the children are looking a little red after spending the day
playing cricket under the autumn sun. Despite it being cold the family
feel comfortable in the space. This is a long way from the scientiﬁc view
of comfort. Szokolay (Szokolay 2004, 17) splits the variables which affect
comfort into three distinct groups.
• Environmental factors, including temperature and humidity;
• personal factors including activity, clothing and acclimatisation;
• and contributing factors including age and gender.
The environmental factors are the physical conditions in a room that can
be measured. Szokolay separates these into four environmental factors
that are closely interdependent; air temperature, humidity, air movement
and thermal radiation (Szokolay 2004, 17). The air temperature and
humidity, the presence of draughts in a room and the surface temperature
of the walls, ﬂoor and ceilings can all be measured. It is more difficult to
measure the personal factors that affect the comfort of a person in a
space.
The environmental parameters Szokolay discusses relate to how people
lose heat from their bodies. The human body core is normally around 37o
C
and is continually losing heat to the surroundings (Lechner 2009, 56). In
order to maintain thermal equilibrium bodies must loose heat at the same
rate that the metabolism produces it. (John, Owen and Steemers 1986,
Figure 14: Diagram of how people loose
heat from their bodies (Source: Lechner
2009)

45
60)The more work done by a person the more heat is generated. For the
family sitting around the table playing a board game there are a range
of personal factors that increase their bodies’ heat output. The game is
competitive, the wine is kicking in and they are all a little burnt from a
day in the sun. In order to remain comfortable this extra heat must be
lost to the environment. Luckily the colder conditions inside the bach are
sufficient for them to remain comfortable.
When thinking about comfort it is essential to have an understanding
of the ways in which the human body loses heat through radiation,
convection and evaporation. (Figure 14) For example, in the cold bach in
the early morning, the family sitting round the table for breakfast with the
sun streaming through the windows would be gaining more radiant heat
from the glass than they were losing to the cold air. By understanding the
ways in which human bodies lose heat architects can design for a larger
comfort zone in order to reduce heating and cooling loads throughout the
year. This though, was not the approach taken by the US Department of
Energy in the 2011 Solar Decathlon. Ironically a competition challenging
the highest levels of energy efficiency sets a strict comfort zone based on
an air temperature range that is impossible to stay within without the use
of mechanical heating and cooling.
For the comfort zone competition the criteria were deﬁned as follows.
Temperature
All available points are earned for keeping the time average interior dry
bulb temperature between 21.7o
C (71.0o
F) and 24.4o
C (76.0o
F) during the
score period.
Humidity
All available points are earned by keeping the time averaged interior
relative humidity below 60% during the score period.
Throughout this project there was an on-going dichotomy between the
goals of the project as an energy efficient kiwi bach and the goal to win
the 2011 Solar Decathlon. Often there were times where the two goals
were contradictory. Keeping the house within a 2.7o
C temperature range

46
is a difficult goal under any conditions, and impossible to achieve without
the use of mechanical heating and cooling, especially considering the
variability of weather in Washington DC at the end of September. The two
goals that were set of designing a winning entry for the competition and
an energy efficient home in NZ were also in opposition. To achieve such
a strict comfort band meant closing the house up and relying on a HVAC
system. This contradicted the design of a kiwi bach that could maintain a
wider comfort range by being opened or closed to the environment based
on the personal ‘comfort’ situation of the user. The following chapters
explain the development of the schematic design in order to achieve
both. The aim was to design a house that could meet the competition
requirements in Washington DC but that could also return to NZ and
operate as a NZ home.
3.2 Climate
“We must begin by taking note of the countries and the climates in which
homes are to be built if our designs for them are correct. One type of
house seems appropriate for Egypt, another for Spain…one still for Rome…
it is obvious that design for our homes ought to conform to a diversity of
climates” The ten books of architecture - Vitruvius
As Vitruvius indicates, designing a building in harmony with climate is an
age old idea and essential for an energy efficient home. For the First Light
house the design had to be optimized for two, quite different climates. The
house had to be presented to the judges of the architecture competition
as a home designed for a Wellington climate. But in order to win the Solar
Decathlon the house had to perform in the measured contests which were
tested during a 10 day period in September in Washington DC. One of the
challenges of the competition is preparing a house for the unpredictable
weather of Washington DC in September. Temperatures and humidity
can vary greatly, from an average high of 23o
C (73o
F) to an average low
temperature of only 5o
C (41o
F) during the period. (Guzowski 2010, 147)
Figure 16 shows the temperature throughout the year in New Zealand and
compares these with Washington DC, highlighting the September period
of the competition. Despite it being autumn in the US the maximum
temperatures are still higher than those experienced in the peak of summer
in Wellington. Accurate and appropriate climate data was essential for the

energy simulations of the house.
Weather files for the initial thermal simulations were sourced from the
US DOE Energy Plus Weather File Database. For the simulations based
in Wellington, the weather files were based on data gathered at the
Wellington International airport and compiled by the New Zealand National
Institute of Water and Atmospheric Research (NIWA). For Washington DC
the information was collected at Ronald Reagan Airport, Arlington, VA
and compiled by the US National Renewable Energy Laboratory (NREL)
These weather files are ideal for simulating and comparing heating and
cooling loads over an entire year because they deal with long term
averages and typical weather conditions. This makes them perfect for the
design of the First Light house for its lifetime within NZ. However, when
designing for only a 10 period in Washington DC they become inaccurate.
Because the weather files represent typical rather than extreme conditions,
it becomes more difficult to design for a possible worst-case scenario
that could occur during the 10 days of the competition. Because of this,
simulations were run for August, September and October rather than
focusing on the 10 day period alone. Design day data was also used where
possible to ensure that the house was designed to meet the potential
worst case scenario climatic conditions during the competition. This was
especially important later on in the design process, when it came to sizing
the HVAC system.
Figure 15: Comparison of temperature and humidity in Wellington and Washington
DC (Source: Autodesk, Ecotect analysis 2011)
Wellington WashingtonDC
Temperature
Humidity

48
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
-10 -10
0 0
10 10
20
30 30
40 40
°C
Dry bulb Temperature Dry bulb Temperature
Monthly averages
Washington DC Wellington NZ
Monthly averages
Temperature °C
Periodof focusforWashingtonDCclimate
Figure 16: Graph of temperatures in New Zealand throughout the entire year
compared with Washington DC
Figure 17: Rain during the 2009 Solar Decathlon (Source: NREL Solar Decathlon,
http://www.ﬂickr.com/photos/44085838@N03/4225695283/)

49
3.3 Thermal modeling - Assumptions
3.3.1 Construction
Before beginning the simulation process it was necessary to make certain
assumptions about the construction of the building and how, when and
where it was likely to be used once it was built.
The initial wall construction used in the baseline model was put together
from information provided in the schematic design proposal. The initial
wall construction used was structurally insulated panels consisting
of 200mm of rigid foam insulation sandwiched between two layers of
oriented strand board. Table 1 presents the building elements used in the
initial thermal model.
ELEMENT DESCRIPTION R-VALUE
Walls SIPS Panels R-6.4
Floor SIPS Panels, Timber Lining R-6.4
Roof SIPS Panels R-6.4
Windows
6mm Standard Glass, Air Filled, Double Glazing,
Aluminum Frames
R-0.26
Skylight
6mm Standard Glass, Air Filled, Double Glazing,
Aluminum Frames
R-0.26
Canopy Timber -
Table 1: Construction R-Values (K·m2
/W) used for baseline simulation

50
3.3.2 Heating and Internal Gains
The only heat gains to the building simulated in the initial baseline model
were those from solar gains through the windows. Internal gains due
to occupants, appliances and lighting loads were added later on in the
design process.
3.3.3 Air exchange – Ventilation and infiltration
The initial natural ventilation rate of 4ACH used in the model defines the
air exchange through opening windows and doors to provide fresh air
to the space. In the simulation this fresh air is added to the space at the
external air temperature at that particular time, taken from the climate
data.
Infiltration is caused by air leakage in the building envelope. In order
to increase thermal comfort and reduce energy consumption it was
important to reduce uncontrolled air movement through infiltration.
The rate of infiltration was modeled at 0.1ACH. At this early stage in the
design process a very high standard for air tightness in the house was set.
Considerable time was spent developing the details of the construction in
order to achieve this.
3.3.4 Modeling Variations
Using the baseline model, several variations were made to the building
fabric in order to reduce heating and cooling loads. Each variation in
the model was simulated independently. This made the effect of the
changing element visible against the original baseline model. The best
performing variations were then compiled incrementally and a simulation
was performed at each step to ensure that the variations that were made
were not opposing each other. For example thermal mass was added to

51
the design to reduce the effect of the internal gains and help with passive
heating of the house during the winter. At the same time the shading
canopy was altered to reduce solar gains. Both changes were modeled
independently and compared to the baseline model. When these elements
were brought together a simulation was performed to ensure that the
increase in shading did not eliminate the effect of adding the thermal
mass.

Figure 18: Ecowool insulation arrives at the construction site in Lyal Bay

53
4 Insulation
Heat loss in a building occurs mainly by transmission through external
surfaces and by infiltration and ventilation through cracks and openings in
the building envelope (Lechner 2009, 463). Significant reductions in these
heat losses will make a significant contribution to energy saving (Szokolay
2004). Insulation is used in buildings in order to reduce heat losses through
the building envelope via conduction, convection and radiation. Insulation
materials have a greater thermal resistance which reduces the rate that
heat energy is transferred through a part of the building to the outside.
The figure which represents the thermal resistance of a building element
is called its R value (m2
.K/W). For a square metre of the building envelope
the R value measures the temperature difference required to transfer one
watt of energy (Vale and Vale 1980, 19), so an R value of 1 means for a
square metre of material a single degree temperature difference between
the outside and the inside will transfer one watt of energy. The greater
the R value the better it is at resisting the transfer of heat. The level of
thermal resistance and the amount of insulation required in a building is
dependent on the climate. In New Zealand insulation has been mandatory
in homes since 1978. Table 2 shows the current building code requirement
for the R value of a building element in Wellington, New Zealand. Older
houses are not required to upgrade to meet current building code standard
and so many New Zealand homes are under insulated. The New Zealand
building code specifies a minimum level of insulation. For the design of a
highly energy efficient building the level of insulation needed to be much
greater. Using climate data for both New Zealand and Washington DC the
model of the house was run through the thermal simulation software and
the R value was increased to find the level of thermal resistance needed
for the optimum performance.
CHAPTER
Year Standard Ceiling Wall Floor Glazing
1978 NZS 4218P:1977 1.9 1.5 0.9 -
2000 NZBC H1/AS1 1.9 1.5 1.3 -
2007 NZBC H1/AS1 2.9 1.5 1.3 0.26
Table 2: NZ Building code requirement of R-value for ceiling, wall, floor & glazing (Source: Isaacs, Thermal
Insulation 2007, 110

54
In order to determine the optimization point at which adding more
insulation would have little or no effect, the expanded polystyrene
insulation thickness in all walls, ﬂoors and ceilings was increased from
12.5mm to 1600mm (0.5” – 63”) doubling the thickness each time. The
corresponding R-values are shown in Table 3.
Polystyrene Thickness (mm) R-Value (m2
°C/W)
12.5mm 0.4
25mm 0.9
50mm 1.7
100mm 3.4
200mm 6.9
400mm 13.8
800mm 27.6
1600mm 55.2
Table 3: Thickness of polystyrene and the corresponding R-Value (m2
°C/W)
The results from the simulation run in a Wellington climate use air
temperature in the space to show the effect of changing levels of
insulation. As can be seen in Figure 19, the increase in insulation by a
magnitude of up to 64 times results in relatively small changes in the
maximum, mean, and minimum temperature over the course of an entire
year in New Zealand. As the amount of insulation increases there is less
of an effect on the internal temperature. Figure 19 shows the optimization
-20
-10
0
10
20
30
40
50
60
R-0.4 R-0.9 R-1.7 R-3.4 R-6.9 R-13.8 R-27.6 R-55.2
Temprature(°C)
Insulation R-value (m2°C/W)
Max Min Mean
Figure 19: Comparison of variation in annual maximum, mean and minimum
internal temperatures (°C) due to increase in insulation R-value (m2
°C/W)

55
point between R-3.4 and R-6.9 for the maximum temperature. For the
mean and minimum temperatures it is more difficult to extrapolate an
optimization point from this graph as both continue to rise slightly up to
an insulation level of R-55, a wall thickness of over one and half metres.
These results gave a good indication of the level of insulation required for
a New Zealand climate, although when the simulation was run through
a Washington DC climate using climate data for the competition period
the results were more conclusive. For the results optimized for the
competition, R values were limited to R2 – R9. Instead of looking at air
temperature the simulation focused on the HVAC load sums for the period
and the peak loads of the HVAC system. The temperature requirements
for the comfort zone contest were used as the set points for the heating
and cooling system.
140
120
100
80
60
40
20
0
R-2 R-3 R-4 R-5 R-6 R-7 R-8 R-9
Insulation R-value (m2°C/W)
HVACEnergyuse(kWh)
Heating Cooling
Optimizationpoint
Figure 9 shows the energy use of HVAC system during the competition and
indicates that when the R value is low adding insulation has a signiﬁcant
impact on the loads of the building. As the levels of insulation increase
the magnitude of its impact on total energy use is reduced. The graph
clearly shows that the optimization point for the insulation during the
competition is between R8-9. This was a signiﬁcant amount of insulation,
especially for a New Zealand climate. Looking at energy use over the
Figure 20: HVAC energy use during competition with an increase in insulation R
value (m2
°C/W)

56
10 days the difference between R6 and R9 is less than 10kWh. Through
discussions with the architecture team it was decided that the extra
cost and complexity in the detailing associated with adding this extra
insulation did not justify the extra energy saving during the competition.
As well as this, the size of mechanical system need to achieve the peak
loads would be the same whether insulation levels of R6 or R9 were used.
It was decided the R6 level of thermal resistance would give a signiﬁcant
energy saving towards achieving the comfort levels of the competition.
Of all materials, dry air has the lowest thermal conductivity (Szokolay
2004, 43). Within a cavity convection currents will allow the transfer of
heat from a warmer place to a cooler place. The purpose of insulation is
to keep the air still, dividing it into small cells with a minimum amount of
actual insulation material in the matrix. As used in the initial simulation,
polystyrene is an effective means of achieving this but there are also other
materials that can be used to achieve similar performance. Sheep’s wool
has been used in New Zealand for generations for its insulating properties.
When wool ﬁbres are packed together, they form millions of tiny air
pockets which trap air, and in turn serve to keep the warmth in during
winter and out in the summer making it an ideal for insulation (Lechner
2009, 464). There are also thirteen times more sheep than people in New
Zealand making it an abundant and sustainable natural resource that tells
a unique story of a very kiwi product, making it perfect for use in the First
Light house. A local NZ company, Ecowool, helped to develop 3 layers
Figure 21: Installation of wool insulation

57
of wool insulation for the house that would achieve the desired level of
thermal performance required from the simulations (Figure 21 and 22).
To achieve a well-insulated thermal envelope it is not just the type of
insulation that is critical to heat loss. In a timber framed building, thermal
bridging can occur where framing has a lower R-value than the insulating
material within the cavities. Heat loss through these weak points in a
building envelope can have a significant impact on the energy use of
a house (Szokolay 2004, 44). Within the initial schematic design SIPs
panels were used as the construction method. Because of this form of
construction there is no heat loss due to thermal bridging. By using wool
insulation within a timber framed wall the detailing of the structure to
avoid thermal bridging became critical to the performance of the walls,
floors and roof. Within the walls a staggered, double stud system limited
thermal bridging to the LVL studs between the modules. Once the details
were developed to avoid thermal bridging the R-value of each of the
building elements was calculated based on the method described in the
New Zealand building code, NZS 4214 (2002) and outlined in Table 4
(Appendix B). Due to the careful consideration of the details and the high
performance of the wool insulation the thermal resistance of the walls,
floors and roof came extremely close to meeting the goals set by the
initial simulations.
Building Element Construction R-value (m2
.°C/W)
Roof 6.48
Wall 5.77
Concrete Floor 5.46
Timber Floor 5.88
Table 4: Construction R-value of individual building elements
Figure 22: Installed wool insulation in roof and wall

58 Figure 23: Thermal mass - the concrete table

59
5 Thermal mass
The initial simulations completed on the baseline model in New Zealand
demonstrated a swing between large extremes in temperatures inside the
space. Ironically the initial design was performing in a very similar way
to a typical New Zealand home, going from very hot in the summer to
very cold in winter. There were a number of reasons for these extremes,
including the type and size of the glazing, placement of shading devices
and amount of natural ventilation. These will be discussed separately in
Chapter 6 and Chapter 7. Another reason for these high temperature
swings is the type of construction in the schematic design. The initial
design consisted of lightweight building materials, high levels of insulation
and a large amount of glazing. In the summer, the lightweight building
construction would overheat due to solar gain through the windows.
As there was no way of storing this excess heat when the heat input
stopped the space cooled down very quickly. In order to reduce these
peak temperatures a simulation was performed that investigated the use
of thermal mass. As the house had to be shipped to the other side of the
world and assembled in only seven days the extent to which mass could
be used in the construction was limited. The initial investigation looked
at the effect on the internal temperature of adding a layer of concrete to
the ﬂoor. The idea was that the mass could capture some of the excess
heat during the day, and utilize it during the night when the ambient
temperature was lower. It would also have the effect of smoothing out
peaks in the internal temperature experienced due to the lightweight
structure’s rapid response to variations in temperature and solar radiation.
CHAPTER
lowanglewintersun
absorbedbyconcretefloorduring theday storedheat releasedduring thenight

60
Figure 24: Artists impression of timber decking running through centre of home
Mass was introduced as a concrete layer in the floor on either side of
the central space. This central space remained a timber floor as initially
modeled. It was decided that keeping the integrity of the timber decking
running through the central space was critical to the architectural concept
(Figure 24). The floor was modeled as solid poured concrete of varying
thicknesses, without any floor coverings, and 240mm of expanded
polystyrene insulation underneath. As with the investigation of insulation,
mass was added at varying thickness to find the optimum level of
performance.
-20
0
20
40
60
Baseline 0.05m 0.1m 0.2m 0.4m 0.8m 1.5m 1.6m
Temperature(°C)
Concrete Thickness (m)
Min Average Max
Figure 25: Variation in minimum, mean and maximum annual internal temperature
with the addition of a concrete topping to the floor

61
Figure 25 shows the effect that the addition of varying thicknesses of
concrete had on the internal temperature in New Zealand throughout the
year. The graph shows that even a small addition of mass reduced the
extremes of temperature within the space.
-8
-6
-4
-2
0
2
4
6
8
10
12
EnergyUse(kW)
15th September
baseline model 100mm concrete
15th October
Figure 26: Variations in HVAC energy use with 100mm concrete slab compared
with baseline for the period from September 15 – October 15
100mm of concrete reduced the minimum and maximum temperature
in the space by close to 10o
C, a signiﬁcant change in peak temperature.
The next simulation focused on the effect 100mm of concrete would have
the peak heating and cooling loads to maintain the comfort zone during
the competition compared with the baseline model. Figure 26 shows
a comparison of the heating and cooling loads required for the house
during this period. Using only 100mm of concrete there would be a 2kW
reduction in the size of the heating system and close to 1kW for cooling.
This is a signiﬁcant reduction in the size of the systems needed to maintain
the comfort zone during the competition.
In order to reduce energy use during the competition the ideal situation
would be to maintain the comfort zone passively, without having to use
the heating and cooling system. Figure 27 shows the internal temperatures
with 100mm of concrete, throughout the competition, compared with the
base line model.

62
The graph shows a smoothing out of the peaks in internal temperature
through the addition of a small amount of mass. The mass passively
regulates the temperature and aids in meeting the strict requirements for
the thermal comfort competition.
0
10
20
30
40
50Temperature(°C)
Time (Hours)
800mm Concrete Baseline 100mm Concrete
15th September 15th October
Figure 27: Variations in hourly internal temperature with 100mm and 800mm
(9.3” & 31.5”) concrete slab compared with baseline for the period from September
15 – October 15
Figure 28: Craning the modules into place on Frank Kitts Park
The transportationof thehomewas
oneof thecomplexities that camewith
theconcreteﬂoor

63
Adding concrete to the design of a modular, transportable home was
always going to be a challenge. 100mm of concrete was presented as
the optimum amount of mass for the space. From the results, though,
even 50mm achieved an improvement in the building’s performance.
Adding thermal mass was important both for the performance during the
measured contests in the competition but also for the development story
presented to the engineering judges. Although having an effect during
the competition the thermal mass would have the greatest impact when
the house was constructed in New Zealand and used over an entire year.
Thermal mass was presented to the judges as a passive solar design
feature that was essential to the engineering of the home. It was decided
that 50mm of concrete was achievable from a detailing and transportation
point of view but that this reduced level would provide the performance
and engineering potential for the competition. In order for the concrete
to perform optimally as thermal mass the next step was to analyze the
glazing in the First Light house to ensure there was enough solar gain for
the mass to perform as intended.
Figure 29: Detailing of the concrete ﬂoor and timber decking
Theconcreteﬂoorwasnot only
anessentialpart of thepassive
designbut abeautiful element in
theFirst Light house

65
6 Glazing and skylight
The schematic design model that was presented to the organizers of the
competition had large amounts of glazing and a central skylight over the
dining space. Glazing was an essential part of the architectural concept
but it was also integral to reducing the house’s reliance on energy for
heating and cooling. In traditional New Zealand homes glazing is the weak
point in the building envelope. With the requirement for window insulation
(double glazing) only being introduced into the New Zealand building
code in 2007, for many New Zealand homes the R value for glazing is very
low. In most cases with only single glazing, heat loss through the windows
is signiﬁcant in increasing the energy consumed for space heating. Even
for homes that meet the building code requirement for double glazing
heat loss through windows is signiﬁcant, often because these are so large.
Double glazing, R-0.26, is almost twice as good at stopping heat loss as
single glazing of R-0.13, but is seven times less effective as an ordinary
insulated stud wall of R-1.9 (Lechner 2009, 484-486). Even the highest
performing windows available on the market are not as effective as a wall
at reducing heat loss. However, during the winter months when the sun is
shining and it is cold outside, north facing windows can be used to heat
the home passively, because, when the sun shines the windows gain more
heat than they lose (Szokolay 2004, 55). Some means of storing this heat
is needed if use is to be made of it when the sun is not shining. Because
windows can collect heat from the sun, the correct sizing, placement and
type of glazing can dramatically reduce energy use during the winter.
During the summer however, without correctly sized shading, windows
can have the opposite effect. In the First Light house the size and type
of glazing was investigated more than any other building element. With
large north facing windows and a glazed skylight, thermal mass and a
highly insulated thermal envelope, glazing became not only key to the
architectural concept but integral to the energy requirements of the home.
Window to wall ratio (WWR) is the measure of the percentage area of
a building’s exterior envelope that is made up of glazing. Using thermal
simulation it is possible to test the performance of the house with different
window to wall ratios. The windows on each façade, including the roof
CHAPTER

66
were modeled together as a percentage of the total wall area. This made
it easier to reduce incrementally the size of the windows on each façade
for the purpose of simulation. The WWR are based on the existing area
of glazing in the model i.e. 100% represents the existing area and 0%
represents no glazing.
The WWR was compared with the maximum, average and minimum
temperatures across a full year. There is a clear correlation between the
glazing area and the internal temperature as shown in Figure 31. Over a
year the average internal air temperature of the original WWR sits at a
comfortable 19.9o
C. At 50% of the original WWR the average temperature
is below 18o
C and drops considerably as the area of glazing is reduced.
The results suggest that the original WWR proposed in the schematic
design proposal was close to the optimal for the First Light house in New
Zealand.
17.9oC 19.9oC
-20
-10
0
10
20
30
40
50
60
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Maximum Average Minimum
Temperature(°C)
Window to Wall ratio
Figure 31: Annual maximum, mean and minimum internal temperature (°C) with
glazing area between 0% and 100% of baseline area
As with previous simulations, the maximum air temperature inside the
space is extremely high. As the window to wall ratio is reduced the
maximum temperature inside the space decreases. The original design
was modeled with the solar canopy which shaded the large north facing
windows during the summer. When the highest temperature was reached
in the simulation these windows were shaded from direct solar gain.
Therefore reducing the WWR on the north façade should have no effect
on the maximum temperature. As the skylight is the only building element

67
0
10
20
30
40
50
60
70
80
90
Temperature(°C)
Time (September 1st - October 31st)
100% 80% 60% 40% 20% 0% Exterior
not shaded the postulation is that reducing the size of the skylight alone
is what was causing the decrease in maximum temperature seen in Figure
31. Consequently, further investigation was required to understand the
direct effect of the skylight on energy use.
The skylight is critical to the architectural concept of the house but
thermally it is also the weak point in the building envelope. Therefore
it was modeled independently from the rest of the house, this time
concentrating on the period of the competition. For these simulations
the shading canopy was removed in order to gain a clear indication of
the correlation between the area of skylight glazing and the internal
temperatures.
From Figure 32 and Figure 33 there is a clear relationship between the
area of the skylight and performance of the First Light house. Reducing
the area of the skylight for the period in Washington DC has a considerable
effect on the peak indoor temperature. If the skylight were removed
completely the maximum indoor temperature would be reduced by 10o
C.
This would have a major impact on the house’s overall energy use for
the competition. The average temperature of the space with the skylight
was 25.2o
C, outside the comfort band for the competition. Without the
skylight the average temperature was reduced to 23.1o
C. Removing the
skylight meant the existing glazing area would be sufficient to achieve
the necessary heat gains for the competition to maintain the house within
the comfort zone. Removing the skylight would signiﬁcantly improve the
performance of the house.
Figure 32: Variations in hourly internal temperature with glazing area between
0% and 100% of baseline area concrete slab compared with exterior for the period
from September 15 – October 15.

68
From a passive performance it is important to understand the effect the
skylight has on comfort but from a competition point of view the real
question is the effect the skylight has on the total energy use of the house.
From the simulation presented in Table 5, it was possible to compare
the total heating and cooling loads during the competition. With the
skylight, the total energy needed to maintain the competition comfort
zone is 214kWh. This was compared to a model where the skylight was
replaced with a roof of the same thermal resistance as the rest of the
house. In this model the energy needed to maintain comfort was 184kWh,
nearly 30kWh less than with the skylight, a signiﬁcant reduction in the
total energy use during the competition period. These results posed an
interesting question to the design team. Was the extra energy needed to
maintain comfort with a skylight the price to pay for a building element
that was critical to the architectural concept?
Cooling energy Heating energy Total
With skylight 76.94 137.50 214.44
Without Skylight 44.53 129.79 184.32
Table 5: Total heating and cooling energy of the house with skylight compared
with no skylight during the competition period
0
10
20
30
40
50
60
70
80
90Temperature(°C)
Time (September 1st - October 31st)
400% 300% 200% 100% 0% Exterior
Figure 33: Variations in hourly internal temperature with glazing area between
100% and 400% of baseline area concrete slab compared with exterior for the
period from September 15 – October 15.

69
As the Solar Decathlon was a competition based on 10 different criteria,
the decision to keep the skylight came down to points. The skylight had
a direct effect on 5 of the 10 contests; architecture, engineering, comfort
zone, energy use and affordability. It was assumed that the skylight, if well
detailed, would be an advantage in both architecture and engineering.
If the mechanical system was sized appropriately and further measures
were taken to shade and insulate the skylight no points would be lost in
comfort. Of course the initial simulations showed that this would increase
overall energy use. But, as there was no limit to the size of the solar array,
this could be easily overcome by adding extra photovoltaic panels to
generate the extra energy. There was an extra cost both for these solar
panels and in detailing the skylight but this was seen as a small price to
pay for the architectural impact of the skylight. It was decided that the
extra points that would be gained in architecture would far outweigh the
points that would be lost from having the extra cost in the affordability
contest. Having committed to the idea of the skylight the next stage of
development focused on how to improve its performance without losing
its architectural impact.
Figure 34: Artist’s impression of the architectural impact of central space showing
the skylight

70
6.1 Skylight Glazing
At this point in the design process the skylight was 19m2
, and spanned
the entire width of the First Light house. To improve its performance
and to allow a services bulkhead to run the length of the house, its size
was reduced to 13.6m2
, 70% of its original size. Initially it was modeled
as a double insulated glazing unit (IGU) with an R value of 0.26. As it
was identified as a major source of heat gain and loss it was modeled
separately to the rest of the windows and a range of different types of
glazing were tested. The glazing itself in the skylight, whether it is plastic
or glass, has almost no thermal resistance. It is the air spaces, the surface
films and the low e coatings which resist the flow of heat. Three different
types of glass were used in the simulations (Low-e + Tint, Low-e, Reflective
+ Tint) in double, triple and quad units, each with argon and air fill giving
a total of 18 variations. In addition to traditional glazing three alternative
high performance overhead glazing materials were tested; Danpalon
Polycarbonate, Pilkington Profilit glass channel with nano-gel, and ETFE
(Ethyltetrafluroethylene) pillows. For comparison the simulations have
also been performed by replacing the skylight with R-6 SIPs, the same
roof detail modeled for the rest of the house. Figure 35 gives construction
details and Table 6 the thermal and optical specifications.
Table 6: Thermal and optical specifications for various glazing types (source:
Window 5)
Glazing Type
W5
ID #
Thick
(mm)
Tsol
Rsol
Tvis
Rvis Emis
K,(W/
m.K)Front Back Front Back Front Back
Standard Clear 9804 6.0 0.77 0.07 0.07 0.88 0.08 0.08 0.84 0.84 1.0
Low-e + Tint 5374 7.9 0.10 0.09 0.56 0.27 0.05 0.04 0.84 0.02 1.0
Low-e 5440 7.9 0.28 0.49 0.56 0.77 0.07 0.06 0.84 0.02 1.0
Reflective + Tint 2751 5.6 0.12 0.63 0.44 0.17 0.6 0.56 0.84 0.84 1.0
Legend:
W5 ID # Window 5 ID number Tvis Visible Transmittance at Normal Incidence
Thick Thickness Rvis Visible Reflectance at Normal Incidence
Tsol Solar Transmittance at Normal Incidence Emis Infrared Hemispherical Emissivity
Rsol Solar Reflectance at Normal Incidence K Conductivity at Normal Incidence (W/m.K)

71
Tvis SHGC U-value
Danpalon Single 0.31 0.44 1.53
Profilit Nano-gel 0.38 0.31 0.19
ETFE 4 Layer 0.8 0.7 1.47
Danpalon Triple 0.36 0.21 0.56
Table 7: Thermal and optical properties of composite skylight glazing options
To compare the different glazing types, design days were used to simulate
the energy used to maintain the comfort zone on a worst case scenario
day in New Zealand. The energy consumed by the HVAC system in kWh for
each of the different options is shown in Figure 36. From the results more
energy is consumed in heating on the coldest day than cooling on the
hottest. This means that heat loss through the skylight is more significant
than the heat gain. In heating, triple glazing performs better than double
due to the extra layer of air. Normally this air space is filled with dry air but
the thermal resistance is increased by replacing the air with argon. From
the four composite glazing options, Nano gel and Danpalon improve the
performance of the skylight by 5-10kWh in heating demand due to their
higher R values. In cooling, though, they all use more energy than the
standard glazing units. The most pronounced example of this is the ETFE
pillow which approximately doubles the cooling load compared with the
glass options. In cooling, the energy use varies more, depending on the
glass type, than the number of layers in the IGU and the type of gas. Adding
a Low-e coating that allows light into the space but not the heat of the sun
is desirable. The type of Low-e coating used in the simulations has a low
solar heat gain co-efficient (SHGC) and is transparent to visible radiation
but reflective to both short wave and long wave infrared radiation. Adding
a Low-e coating improves the performance of the house in cooling load
by over 5kWh.
Figure 35: Composite skylight glazing construction details (a) Triple Layer
Danpalon with translucent glass wool insulation, (b) Profilit glass channel with
nano-gel insulation, (c) ETFE 4 layer pillow
Danpalon
Glass channel with nano-gel
ETFE pillow

72
The previous simulation concluded that the best performing glazing option
was quad glazing, with an argon fill and a Low-e coating. This is based on
the extremes of temperature over an entire year in New Zealand. Looking
at heat gain and heat loss, Figure 37 explores the effect of different types
of glazing during the competition period. Compared to the previous
simulation, heat loss is insignificant. Differences between the various
types of glazing are minimal, with the exception of the Nano-gel which
offers a significant reduction. Heat gain on the other hand is substantially
higher during the competition period and so the effect of adding a
Low-e coating and tint to the glass is more pronounced. The single layer
polycarbonate, Nano-gel and ETFE all perform very poorly and result in
higher heat gain, almost double in the case of the ETFE (9.7kW peak),
while the triple layer Danpalon is in the same range as the glass options.
From these results the composite glazing options were discarded and it
was decided a standard glazed skylight would be designed. Of the best
performing options the difference between the quad and triple glazing
was insignificant, especially during the competition. Argon gas offered
the greatest thermal resistance against heat loss and a Low-e coating with
a tint had the greatest impact on heat gain.
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
low-e+tint
low-e
reflect+tint
low-e+tint
low-e
reflect+tint
low-e+tint
low-e
reflect+tint
low-e+tint
low-e
reflect+tint
low-e+tint
low-e
reflect+tint
low-e+tint
low-e
reflect+tint
Polycarbwtint
25mmNanoGel
EFTE-4Layer
Danpalon-V3
SIPR-2
SIPR-4
SIPR-6
SIPR-8
SIPR-10
Air Argon Air Argon Air Argon
Double Triple Quad Composite No Skylight
HVACEnergyUse(kWh)
Skylight Type
Cooling energy Heating energy
Figure 36: Skylight Constructions - Design Day HVAC Energy Use (kWh)

73
Up to this point the simulations were based on theoretical glazing types.
Triple IGU, Low-e coating and an argon fill was the optimum glazing
specification for the skylight. These specifications were taken to Metro
Glass, a local glass manufacturer and a glazing unit was selected based on
this criteria. Their specifications are outlined in Table 8 and were input into
the simulation. The initial glazing options Metro Glass supplied performed
extremely well at reducing heat loss (better than any of the glazing
options previously tested), although there were significantly higher heat
gains than expected. This was resolved in further iterations by replacing
the outer layer of clear glass with a tinted glass that excluded more solar
radiation while still allowing an acceptable visible light transmission into
the space. In addition to thermal simulation, day lighting analysis was
performed on the skylight in order to ensure there were sufficient indoor
light levels (Figure 38).
0.000
1.000
2.000
3.000
4.000
5.000
6.000
7.000
8.000
9.000
10.000
Low-E&Tint
Low-E
Reflect&Tint
Low-E&Tint
Low-E
Reflect&Tint
Low-E&Tint
Low-E
Reflect&Tint
Low-E&Tint
Low-E
Reflect&Tint
Metro1.1
Metro2.1
Low-E&Tint
Low-E
Reflect&Tint
Low-E&Tint
Low-E
Reflect&Tint
Polycarbwtint
25mmNanoGel
EFTE-4Layer
Danpalon-V3
SIPR-2
SIPR-4
SIPR-6
SIPR-8
SIPR-10
Air Argon Air Argon Air Argon
thgilykSoNetisopmoCdauQelpirTelbuoD
HeatTransfer(kW)
SkylightType
Heat Gain (kW) Heat Loss (kW)
Figure 37: SEffect of different types of glazing on heat loss and gain through the
skylight during the competition

74
Glazing Type
Thick
(mm)
Tsol
Rsol
Tvis
Rvis Emis K (W/
mK)Front Back Front Back Front Back
Standard Clear 5.7 0.77 0.07 0.07 0.88 0.08 0.08 0.84 0.84 1.0
Argon Gas 12 0.026
ClimaGuard® Neutral 70 5.7 0.558 0.18 0.13 0.75 0.05 0.07 0.17 0.84 1
Argon Gas 12 0.027
ClimaGuard® Neutral 70 5.7 0.558 0.18 0.13 0.75 0.05 0.07 0.17 0.84 1
Legend:
Tvis
Visible Transmittance at Normal
Incidence
Thick Thickness Rvis
Visible Reflectance at Normal
Incidence
Tsol
Solar Transmittance at Normal
Incidence
Emis Infrared Hemispherical Emissivity
Rsol Solar Reflectance at Normal Incidence K Conductivity at Normal Incidence
Table 8: Thermal and optical specifications for Metro Glasstech intial suggested IGU (source: Metro Glasstech and
Window 5)
Figure 38: Daylight anaylsis of the skylight preformed in Autodesk Ecotect
Analysis software

75
6.2 Skylight Shading
One of the ideas that developed from the concept of the bach was
that users had control over their own space. Even with the extensive
investigation into the best performing glazing system the user had no
control of the effect the skylight had on their comfort. The results from
both simulations above show that even with the best performing glazing
system, the skylight created large cooling loads during the summer and
even bigger heating loads during the winter. During the competition,
heat gain through the skylight had the greatest impact on energy use
therefore shading was a key strategy that was investigated for achieving
thermal comfort. The greatest challenge in adding shading to the design
was detailing the shading device so it did not detract from the effect
of the skylight. For the initial simulations the visual impact was ignored
and the shading was modeled as 300mm external and internal louvers at
three different settings, 60° open, 30° open, and fully closed. At this stage
there was no need to worry about aesthetics in the world of simulations.
Figure 39 shows the maximum, mean and minimum temperatures with
the different louver variations. As can be seen in this graph the minimum
internal temperature stays the same throughout the simulations, at -12°C
(10.4°F) on the coldest winter day. As expected the shading has no
effect during cold winter days. The most prominent change is the drop
in maximum temperature when the skylight was fully shaded with the
external louvers closed. This results in the internal temperature dropping
from 54.8°C (129°F) in the baseline model to 39.6°C (103°F). This clearly
demonstrates the signiﬁcant impact the skylight has on the internal
temperature and the importance of reducing the solar gain during the
summer.
Detailing for the shading system so that it ﬁtted with the architectural
concept was easy to control and construct, and was as affordable, was

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